Methods and Devices for Puncturing Tissue

ABSTRACT

Novel and unique medical devices and associated methods are disclosed, for a medical device for puncturing tissue at a tissue site. The medical device is an elongate member having a proximal section, a distal section, and a rail section therebetween. The medical device includes an active tip at a distal end of the distal section and is operable to deliver energy to create a puncture through the tissue. The rail section is configured to both act as a rail for supporting installation of one or more tubular members thereupon, as well as be maneuverable for enabling access to the tissue site.

CROSS REFERENCED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/445,790, filed on Jun. 19, 2019, which is a continuation of U.S.application Ser. No. 14/910,525, filed on Feb. 5, 2016, which is anational phase entry of PCT/IB2013/060286, filed on Nov. 20, 2013, whichclaims benefit of U.S. application 61/863,265, filed on Aug. 7, 2013 andclaims benefit of U.S. application 61/863,579 filed on Aug. 8, 2013.

TECHNICAL FIELD

The disclosure relates to devices, systems and methods used to gainaccess to various tissue sites from particular access sites, and inparticular to devices and associated methods used to access the leftside of a heart via puncturing tissue.

SUMMARY OF THE DISCLOSURE

In one broad aspect, embodiments of the present invention comprise amedical device for puncturing tissue at a tissue site. The medicaldevice is an elongate member having a proximal section, a distalsection, and a rail section therebetween. The medical device includes anactive tip at a distal end of the distal section and is operable todeliver energy to create a puncture through the tissue. The rail sectionis configured to both act as a rail for supporting installation of oneor more tubular members thereupon, as well as be maneuverable forenabling access to the tissue site.

In the aforementioned embodiments, the distal section defines a distalsection curved portion and a distal section straight portion, where thedistal section straight portion is distal to the distal section curvedportion. A further embodiment of the present invention has the elongatemember comprising a reverse taper. The reverse taper increases in outerdiameter from the distal end of the distal section curved portion to thedistal section straight portion. In an embodiment of the presentinvention, the distal section defines a distal section curved portionconfigured to automatically form a distal coil in a deployed state foranchoring the distal section upon the distal section being advancedthrough the puncture. Further, the coil is configured such that, upondeployment from a confined state, along an axis of advancement, theactive tip curves away from the axis of advancement. Additionally, thedistal section further comprises a distal section straight portion,distal to the distal section curved portion. The distal section straightportion includes the active tip. In some embodiments, the distal sectionstraight portion has a length of about 3 mm to 10 mm. In someembodiments, the distal coil is configured as a double pigtail curve. Inanother embodiment of the present invention, the elongate member is aconductive guidewire. The electrically conductive guidewire issubstantially covered by a layer of electrical insulation with a distaltip of the electrically conductive guidewire exposed. Further, theguidewire comprises an exposed portion on the proximal section forcoupling to a source of electrical energy. In some embodiments, theactive tip is substantially atraumatic. In some embodiments, the medicaldevice includes a radiopaque marker positioned on the distal section. Inanother embodiment, the radiopaque marker comprises a helical coilaround the elongate member at the distal section. In some embodiments,the active tip comprises an electrode. Further, the electrode is domeshaped.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be readily understood, embodiments ofthe invention are illustrated by way of examples in the accompanyingdrawings, in which:

FIG. 1 is an illustration of a system in accordance with an embodimentof the present invention;

FIG. 1A is an illustration of a dilator in accordance an embodiment ofthe present invention;

FIG. 1B is an illustration of a steerable sheath for use with a dilatorin accordance with an embodiment of the present invention;

FIG. 1C is an illustration of a dilator in accordance with an alternateembodiment of the present invention;

FIGS. 1D-1E illustrate a dilator within a steerable sheath in accordancewith various embodiments of the present invention;

FIGS. 2A-2C illustrate a dilator in use with a steerable sheath, inaccordance with various embodiments of the present invention;

FIGS. 3A-3E illustrate various distal tip configurations of a dilator inaccordance with an embodiment of the present invention;

FIG. 4 illustrates an embodiment of a steerable sheath suitable for usewith an embodiment of a dilator of the present invention;

FIG. 5A is a side view of an embodiment of a medical device, for examplea multi-function guidewire of the present invention;

FIG. 5B includes side views of an internal metal wire of amulti-function guidewire in a straight configuration and a correspondingcoiled configuration;

FIG. 5C is an exterior view of detail “A” of FIG. 5A;

FIG. 5D is a cross section view of detail “A” of FIG. 5A;

FIG. 5E is an exterior view of the distal section straight portion of acurved distal section;

FIG. 5F is a cut-away view of section A-A of FIG. 5D;

FIGS. 6A-6D illustrate a wire and dilator used in conjunction with asteerable sheath, in accordance with embodiments of the presentinvention; and

FIGS. 7A-7G illustrate a further embodiment of a method of using asystem in accordance with embodiments of the present invention toperform a transseptal puncture from a superior access approach.

DETAILED DESCRIPTION

In some medical applications, it may be desirable to reach a desiredtarget tissue site within a region of tissue within a patient's body inorder for example, to provide access to a particular cavity or space. Insome applications access to the cavity or space may be provided througha puncture that is created within the desired tissue site. In order toinitially reach the desired tissue site within the region of tissue,access may be provided into and/or through vasculature using aguidewire. A sheath and dilator assembly may then be advanced over theguide wire, and the sheath may be used to guide the dilator, as well asany other devices positioned through the assembly, to the desired targettissue site.

In some such applications, a particular access point into the patient'svasculature may be dictated by, for example, treatment requirements oranatomical considerations. For example, patients with occluded orstenosed vasculature may require an alternate access point. In addition,procedures such as lead placement dictate particular access points inorder to allow implanted leads to be connected to a battery.

Thus, in certain procedures, a particular tissue puncture site isrequired while the access point into the vasculature is also restricted.In some such procedures, delivering treatment tools and assemblies fromthe access point to the tissue puncture site is difficult and/or mayrequire many device exchanges due, for example, to the curvature and/ortortuosity of the vasculature within that region of the body.

For example, in some such applications, a very sharp or high curve ortrajectory may be required to access the desired tissue site. In orderto reach the desired tissue site, fixed curve sheaths or steerablesheaths may be utilized but both have drawbacks when used with currentaccessory devices.

In particular, where a fixed curve sheath is used, the fixed curvesheath may not be able to retain its curvature. This may be a result ofa relatively stiff dilator and/or other devices inserted within thefixed curve sheath. As such, the sheath may not be able to position thedilator and/or any other device at the desired target tissue site.

In situations where a steerable sheath is utilized, upon actuation ofthe steerable sheath (in some such embodiments), the stiffness of thedilator, and/or any additional devices inserted through the steerablesheath, may limit or prevent the steerable sheath from reaching theintended or required curvature, thus preventing the steerable sheathfrom positioning the dilator and/or other devices at the target tissuesite. Furthermore, stiffness of the dilator may result in breakage ofthe actuation mechanism of the steerable sheath upon actuation of thesteerable sheath. In one particular example, the pull wires may separatefrom a distal joint within the sheath or may separate from the proximallever or actuation mechanism of the steerable sheath. In other examples,the stiffness of the dilator may result in breakage of the pull wiresupon actuation of the steerable sheath.

In addition, as mentioned above, puncturing certain tissue sites whilebeing limited to particular access points also often requires exchangingdevices multiple times, with each device performing a specific functionduring the course of the procedure. For example, current methods ofaccessing a heart chamber on the left side of the heart using a superioraccess approach require multiple device exchanges resulting inrelatively inefficient and lengthy procedures. In a further example ofprocedural inefficiencies, existing techniques for gaining transeptalaccess for delivery of cardiac leads generally require that thetransseptal puncture and lead delivery be performed using differentaccess points, necessitating, for example, either transferring the lead,or trying to re-locate the puncture site, and then installing the leadwithin the heart.

The present inventors have conceived and reduced to practice novel andunique devices (which may be referred to as “hybrid devices” in thedescription below) and associated methods to facilitate efficient andrepeatable puncture of a plurality of tissue sites while allowingvascular access from various access points on a patient's body. Thesedevices include dilators and wires, for example guidewires, usable aloneor in combination to facilitate this tissue access and puncture atvarious anatomical locations from desired access points.

For example, the present inventors have conceived and reduced topractice a flexible dilator that is usable in combination with anancillary medical device (which may include a catheter, a fixed curvesheath or a steerable sheath), the dilator being designed and configuredso that it does not substantially affect the curvature of the ancillarydevice.

Embodiments of a dilator of the present invention are sufficientlyflexible to allow the ancillary device to guide and position the dilatorand/or additional devices in a wide array of patient anatomies.Embodiments of the dilator accomplish this function by providing aflexible intermediate region having reduced stiffness. The location ofthe flexible region, when the dilator is inserted into/through theancillary device, corresponds to a region of the ancillary device thatis amenable to deflection or has a particular shape or curve, wherebythe flexibility of the dilator at that location helps to ensure that thedilator does not substantially impair the ability of the ancillarydevice to retain, maintain or reach its intended shape or curvature. Insome embodiments, the dilator, while being sufficiently flexible alongthe intermediate region, has sufficient stiffness along a distal endregion to allow the dilator to be tracked or advanced across tissue fordilating a perforation or puncture at the desired target tissue site.

Relatedly, the present inventors have discovered, and reduced topractice, guidewire-based medical devices for puncturing a septum of theheart and for providing reliable and robust guidewire rail supportacross the puncture even when accessing the heart via veins superior tothe heart (such as the subclavian veins). Such medical devices aresufficiently flexible to be directed towards the appropriate puncturesite from the desired access point, yet are also stiff enough to supportinsertion of additional devices thereupon. In addition, embodiments ofsuch devices include features for maintaining the medical device inposition across the puncture to maintain patency of the puncture and toensure continued access to tissue across the puncture.

Furthermore, the present inventors have conceived and reduced topractice methods of treatment that employ one or more novel devices forpuncturing tissue sites utilizing defined access points and forperforming multiple steps of the procedure to thereby reduce and/orminimize the number of device exchanges. In addition to improvingefficiencies and reducing treatment procedure time, these methods allowfor transseptal puncture and lead delivery to be performed using asingle access point.

With specific reference now to the drawings in detail, it is stressedthat the particulars shown are by way of example and for purposes ofillustrative discussion of certain embodiments of the present inventiononly. Before explaining at least one embodiment of the invention indetail, it is to be understood that the invention is not limited in itsapplication to the details of construction and the arrangement of thecomponents set forth in the following description or illustrated in thedrawings. The invention is capable of other embodiments or of beingpracticed or carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein is for the purposeof description and should not be regarded as limiting.

Systems

FIG. 1 is an illustration of a system 50 that incorporates embodimentsof devices of the present invention and that may be utilized during thecourse of an inventive procedure as described further hereinbelow. Asillustrated, system 50 includes a steerable device such as steerablesheath 300 with dilator 100 inserted therein, and wire 200 inserted intodilator 100. Steerable sheath 300 and dilator 100 each defines arespective lumen through which devices may be inserted, and maytherefore be referred to as “tubular members”. Although a steerablesheath is discussed throughout this application, it will be evident toone of skill in the art that other steerable devices or articulatingcomponents may be used. For ease of explaining the fundamentalprinciples of the invention, “Steerable Sheath” will be used throughoutthe specification as an example of a steerable or articulating device.Alternatively, in some embodiments, a fixed curve sheath may be utilizedin place of an articulating sheath, depending on the access point andtissue puncture site chosen by a user.

Wire 200 is connected to a generator 500 by connector 502. Steerablesheath 300 includes a steerable sheath handle 302. In some embodiments,the steerable sheath is unidirectional i.e. it allows deflection in asingle direction. In other embodiments, a bi-directional sheath may beused. In the exemplary applications disclosed below, an 8.5 Frenchsteerable sheath with a 40 cm usable length is typically used;procedures for larger patients may use a sheath with a 45 cm usablelength or other lengths as may be appropriate. FIG. 1(i) shows anexpanded view of a portion of heart 400 illustrating a distal portion ofsteerable sheath 300, distal tip 106 of dilator 100, and wire 200, whichmay be a radiofrequency puncture wire.

Dilators

In accordance with one embodiment of the present invention, as shown inFIG. 1A, a flexible dilator 100 is disclosed for use with a steerablesheath 300 (shown in FIG. 1B) to access a region of tissue within apatient's body. The steerable sheath 300 has a range of deflectionangles and can achieve a range of curvatures upon actuation. Referringagain to FIG. 1A, the dilator 100 comprises a dilator hub 102 that iscoupled to an elongate member 120 that comprises regions of varyingflexibility including an intermediate region 100 b that terminates in adistal end region 100 a. In accordance with an embodiment of the presentinvention, the intermediate region 100 b is a substantially flexible orsoft section that provides minimal resistance to deflection and isoperable to be deflected under guidance to allow the dilator 100 toreach a desired site within a region of tissue within the patient's bodyto facilitate advancement of the distal end region 100 a there-through.The flexible intermediate region 100 b allows the dilator 100 to conformto the curvature of the steerable sheath 300 that is achieved throughactuation of the steerable sheath 300. Thus, in some embodiments, asoutlined herein, the flexible intermediate region 100 b does not inhibitthe range of motion of the steerable sheath 300.

Additionally, the elongate member 120 of the dilator 100 furthercomprises a distal end region 100 a that is formed distally adjacent tothe flexible intermediate region 100 b, such that the flexibleintermediate region 100 b continues distally until (and terminates at) aproximal boundary or edge of the distal end region 100 a. In other wordsthe distal end region 100 a extends proximally from the distal edge ofthe dilator 100 until a distal edge of the flexible intermediate region100 b. The distal end region 100 a has a stiffness or rigidity that isgreater than the flexible intermediate region 100 b to facilitateadvancement of the dilator 100 through the tissue once the dilator 100has been positioned at the desired tissue site, such as a desiredpuncture site. The stiff or substantially rigid distal end region 100 aprovides enhanced pushability and may prevent deformation thereof duringadvancement of the distal end region 100 a through the tissue (forexample over a guide-wire or a puncturing device), for example at thepuncture site in order to dilate the puncture site.

In one particular example, the elongate member 120 and the hub 102 maybe formed, for example using techniques as may generally be known in theart, such as molding techniques. In some embodiments, the distal endregion 100 a is formed from a rigid polymer, and the intermediate region100 b is formed from a flexible polymer. In one particular embodiment,the rigid distal end region 100 a is formed from High DensityPolyethylene (HDPE) and the flexible or soft intermediate region 100 bis formed from Low Density Polyethylene (LDPE). In some embodiments, theflexible intermediate region 100 b may be formed from a material thatexhibits sufficient flexibility to enable the flexible intermediateregion 100 b to conform to the curvature of a steerable sheath 300 andsubstantially does not impair, limit or inhibit the ability of thesteerable sheath 300 to reach its intended curvature. Additionally, therigid distal end region 100 a is formed from a material that exhibitssufficient rigidity that to enable the rigid distal end region 100 a tobe advanced through a tissue site such as through a puncture site withina region of tissue. Thus, dilator 100 can be understood to be a hybriddevice in that it is sufficiently flexible to be guided to the tissuesite yet maintains sufficient rigidity to be advanced through the tissuesite.

As outlined previously, in accordance with an embodiment of the presentinvention, a dilator 100 is provided that is usable with a steerablesheath 300 to access a region of tissue within a patient's body. Thesteerable sheath 300 may be of the type shown in FIG. 1B comprising anarticulating portion or deflectable region 200 b that is amenable todeflection upon actuation of a steerable actuation mechanism for examplesuch as a knob of a handle 302. During use, the dilator 100 is insertedwithin the steerable sheath 300 for use therewith such that a locationor position of the flexible intermediate region 100 b of the dilator 100corresponds to the articulating portion or deflectable region 200 b ofthe steerable sheath. This enables the steerable sheath 300 to reach itsallowable range of curvatures or deflection (as shown and discussedlater with reference to FIGS. 2A-2C), upon actuation, as minimalresistance is introduced by the dilator 100. In other words, theflexible intermediate region 100 b of the dilator does not impartrigidity to the steerable sheath 300 as the dilator 100 is being steeredby the steerable sheath 300. This enables the steerable sheath 300 toposition the distal end region 100 a of the dilator 100 at a desiredtarget location within a region of tissue such as at a desired puncturelocation or site to enable the distal end region 100 a to subsequentlyadvance there-through for example to dilate the puncture site.

In one particular embodiment, with reference to FIG. 1A, dilator 100further comprises a proximal region 100 c that forms a part of elongatemember 120 of dilator 100. The proximal region 100 c extends proximallyfrom the flexible intermediate region 100 b. More specifically, theproximal region 100 c extends proximally from a proximal boundary of theflexible intermediate region 100 b and may extend until the hub 102. Insome embodiments the proximal region 100 c may also be formed from aflexible material and exhibits flexibility. Alternatively, in otherembodiments, as shown in FIG. 1C, the flexible intermediate region 100 bmay extend along the proximal region 100 c and may include the proximalregion 100 c. In some such embodiments, the flexible intermediate region100 b may have varying regions of flexibility. In some examples, aproximal region 100 c is provided that is flexible as this may bedesirable in certain applications. In some examples, flexibility of thedilator 100 in the proximal region 100 c may lead to buckling observedin segment 112 of the proximal region 100 c of the dilator 100 as thedilator is inserted into the steerable sheath 300, as shown in FIG. 1D.In some such embodiments, it may be desirable to provide stiffness orrigidity to the device proximal region 100 c in order to make thedilator 100 less susceptible to buckling.

Therefore, in some embodiments as shown in FIG. 1E, a dilator 100 isprovided where the proximal region 100 c has a rigidity that is greaterthan that of the flexible intermediate region 100 b. In someembodiments, the rigid proximal region 100 c is formed from a materialthat exhibits sufficient rigidity to enable the rigid proximal 100 c tobe advanced through the steerable sheath 300 substantially withoutbuckling or deforming. The rigidity of the dilator 100 in the proximalregion 100 c reduces the likelihood of the dilator bending or deformingas it is being inserted into the steerable sheath 300 during aprocedure. In some embodiments, the distal end region 100 a and theproximal region 100 c have substantially the same rigidity. In aparticular embodiment, the rigid distal end region 100 a and theproximal region 100 c are formed from a rigid polymer and the flexibleintermediate region is formed from a flexible polymer. In one example,the rigid distal end region 100 a and the proximal region 100 c comprisesubstantially the same stiffness. In other embodiments, the rigidity ofthe rigid distal end region 100 a and the proximal region 100 c maydiffer. In one particular embodiment, the rigid distal end region 100 aand the proximal region 100 c are formed from High Density Polyethylene(HDPE) having a stiffness that is equal to about 0.8 GPa, whereas, theflexible intermediate region 100 b is formed from Low DensityPolyethylene (LDPE) having a stiffness of about 0.3 GPa. In otherembodiments, the flexible and rigid regions of the dilator maybe formedfrom PEBAX® with different durometers of PEBAX® being used for therespective flexible and rigid regions.

In some embodiments, the dilator 100 has a usable length (i.e. thelength of the elongate member 120) that is between about 60 cm to about100 cm. More specifically, in one example, the dilator has a usablelength of between about 67 cm and 68 cm. In a specific example of this,the dilator has a usable length of about 67.6 cm. In another example,the dilator has a usable length of between about 70 cm to about 71 cm.In a specific example of this, the dilator has a usable length of about70.6 cm.

In some such embodiments, the flexible intermediate region 100 b has alength of between about 7 cm to about 15 cm. In one particular example,the flexible intermediate region has a length of about 15 cm.

In some embodiments, the distal end region 100 a has a length of betweenabout 0.4 cm to about 4.0 cm. In a specific embodiment, the distal endregion 100 a has a length of about 0.5 cm to about 1 cm. In a particularexample of this, the distal end region 100 a has a length of betweenabout 0.6 cm to about 0.7 cm. In a specific example, the distal endregion has a length equal to about 0.7 cm. In some embodiments, therigid distal end region 100 a has a length of between about 2.5% toabout 60% of the length of the flexible intermediate region.

In some embodiments, the rigid proximal section 100 c may have a lengthof between about 41 cm to about 92 cm. In one particular embodiment, theproximal end section 100 c has a length of about 51 to about 52 cm. In aspecific example of this, the proximal end section has a length of about51.9 cm.

With reference now to FIGS. 2A-2C, various embodiments of a steerablesheath 300 are shown with the dilator 100 inserted there-through. Insome embodiments, once the dilator 100 has been inserted through thesteerable sheath 300, the dilator 100 extends by a distance, for exampleabout 3 cm, distally beyond the distal end or tip of the steerablesheath 300 (more specifically, beyond the distal end/edge of thesteerable sheath 300). In some embodiments, the dilator extends bybetween about 2 cm to about 4 cm beyond the distal edge of the steerablesheath 300. In some embodiments, the steerable sheath 300 has a usablelength 201 that is between about 45 cm to about 71 cm.

In one specific example, with reference now to FIG. 2A, the steerablesheath 300 is an 8.5 French unidirectional steerable sheath, that has adeflectable region or articulating portion 200 b operable to adopt acurve S having an angle of about 180 degrees and a having a radius ofcurvature of about 8.5 mm. Alternatively, in the example as shown inFIG. 2B, the deflectable region or articulating portion 200 b of thesteerable sheath 300 is operable to adopt a curve M having a radius ofcurvature of about 11 mm. In another example as shown in FIG. 2C, thedeflectable region or articulating portion 200 b of the steerable sheath300 is operable to adopt a curve L, having a radius of curvature equalto about 25 mm.

With reference again to FIGS. 2A to 2C, in some embodiments, the usablelength 201 of the steerable sheath 300 is equal to about 45 cm. In somesuch embodiments, the steerable sheath 300 is used with an 8.5 Frenchflexible dilator 100 having a usable length of about 67 cm andcomprising a flexible intermediate region 100 b with a length of about15 cm. Thus, in accordance with various embodiments of the presentinvention, a steerable sheath 300 and dilator 100 are provided that workin conjunction with each other, with the steerable sheath 300 anddilator 100 having suitable lengths and sizes (including inner and outerdiameters) that are usable to reach a desired region of tissue wheninserted through the vasculature.

With reference now to FIGS. 3A-3D, various dilator distal tipconfigurations are shown with alternative distal end regions 100 a. Inthe particular example shown in FIG. 3A, the dilator 100 comprises ataper 122 along a distal end of the dilator 100, forming a tapereddistal tip 106. In the example shown, the distal end region 100 aextends partially along the length of the taper 122 and as such forms apart of the taper 122. In a specific example of this, the taper 122 hasa length of about 1 cm. In one such example the rigid distal end region100 a has a length of about 0.7 cm. In another such example, the rigiddistal end region 100 a has a length of between about 0.3 cm to about0.5 cm.

FIGS. 3B, 3C and 3D illustrate alternative configurations for thetapered distal tip 106. As shown in FIG. 3B, in some embodiments, thedistal end region 100 a may extend along the entire length of the taper122. In a further example of this, as shown in FIGS. 3C and 3D, thedistal end region 100 a may additionally extend further proximally alongthe elongate member 120, beyond the taper 122.

FIG. 3C illustrates a dilator 100 that is an 8.5 French dilator thattapers down to an outer diameter (OD) of about 0.046″ (about 1.2 mm) andan inner diameter (ID) of about 0.036″ (about 0.9 mm), along the tapereddistal tip 106. In a specific example, the taper 122 has a length ofabout 2 cm. In some such embodiments, the distal end region 100 a has alength of about 3 cm and is formed from HDPE, whereas the flexibleintermediate region is formed from LDPE. The dilator 100 may be formedfrom a re-flow of the two polymers, HDPE and LDPE, in a glass die vialap joining.

Additionally, FIG. 3D illustrates a dilator 100 that has a distal tip106 that comprises a double taper configuration. In one specificexample, the dilator 100 is an 8.5 French dilator that tapers down toabout 5.6 French along a first tapered region R1, with the first taperedregion R1 having a length of about 1 cm. The dilator 100 then tapersfrom about 5.6 French to an outer diameter (OD) of about 0.046″ and aninner diameter (ID) of about 0.036″, along a second tapered region R2,with the second tapered region have a length of about 1 cm. In onespecific example, the distance between the first and second taperedregions R1 and R2 is also equal to about 1 cm. In one such example, thedistal end region has a length of about 4 cm. The dual taperconfiguration may provide greater feedback during dilation and may allowthe user to feel the tactile feedback (in the form of a pop) associatedwith each of the first and second tapered regions R1 and R2. The dualtaper configuration may be formed in a similar manner to above, using aglass tipping die via lap joining.

In some embodiments, the dual taper distal tip configuration shown inFIG. 3D may require less force to advance it through a tissue site (forexample, through a puncture within a region of tissue) than a singletaper distal tip configuration, as shown FIGS. 3B and 3C. Furthermore,in some examples, a longer taper length (as shown and discussed withrespect to FIG. 3C) may require less force to be advanced through tissuethan a shorter taper length (as shown in FIG. 3A). The longer taperprovides a lower slope and hence a smoother transition. Additionally,the longer taper length may prevent high mechanical resistance when thedilator is advanced through a puncture site and may prevent the dilatorfrom slipping away from the puncture site. Additionally, in exampleswhere the dilator is used to dilate a puncture within a septum of theheart (where access is provided through the right atrium and an RF wireis used to create the puncture as described further below), the longertaper length may prevent the RF wire from being pulled back into theright atrium of the heart and losing the puncture site and thus may helpprevent the need to create a second puncture.

Furthermore, in some embodiments, the dilator 100 comprises a straightdilator that substantially lacks a curvature. In other words, thedilator 100 has a substantially straight configuration along each of therigid proximal region 100 c, the flexible intermediate flexible portion100 b and the rigid distal end region 100 a. During use, the straightdilator 100 does not impart a curvature to the steerable sheath 300 toenable the steerable sheath 300 to reach its desired curvature uponactuation. This allows the steerable sheath 300 to position the distalend region 100 a at a desired target location, for example at a desiredpuncture site to enable the distal end region 100 a to advancethere-through to dilate a puncture once it has been formed. Therefore,the straight dilator 100 does not interfere with or affect the intendedcurvature of the steerable sheath 300 and thus does not inhibit thedesired range of motion of the steerable sheath 300. In accordance withan embodiment of the present invention, the dilator 100 comprises both astraight configuration and a flexible or soft intermediate region 100 b,and the combination provides a synergistic or combined effect preventingthe dilator 100 from inhibiting the range of movement of thearticulating portion or deflectable region 200 b of the steerable sheath300. This may allow the steerable sheath 300 to guide the dilator 100 toaccess a region of tissue within a patient's body such as for example anarea of the heart.

In a specific example, as shown in FIG. 3E, a dilator 100 is providedthat is an 8.5 French dilator. Along the proximal region 100 c andflexible intermediate region 100 b (not including the taper 122), thedilator has an outer diameter (OD) that is equal to about0.111″+/−0.002″ and an inner diameter (ID) that is equal to about0.058″+/−0.002″, that tapers down along the tapered distal tip 106 to anouter diameter of about 0.044″+/−0.001″ and an inner diameter of about0.036″+/−0.001″ at the distal boundary or edge of the distal tip 106.This allows the dilator 100 to be compatible with a 0.035″ ODguide-wire. Furthermore, the taper 122 along the tapered distal tip 106has a length of about 1 cm and the rigid distal end region 100 a has alength of about 0.7 cm. In one such example, the dilator 100 has ausable length of about 67.6 cm, with the flexible intermediate region100 b having a length of about 15 cm, with the rigid proximal region 100c having a length of about 51.9 cm. In one particular embodiment, therigid distal end region 100 a and the proximal region 100 c are formedfrom High Density Polyethylene (HDPE) having a stiffness of 0.8 GPa,whereas, the flexible intermediate region 100 b is formed from LowDensity Polyethylene (LDPE) having a stiffness of about 0.3 GPa. In theexample described herein, the dilator 100 comprises varying regions offlexibility (i.e. flexible and rigid regions), and since the dilator 100comprises a fairly constant OD and ID, the behavior or various regions,in terms of rigidity, is governed by the stiffness of the materialsused.

In embodiments described herein, the flexural rigidity value of thedilator 100 is the product of Young's modulus E (in Pa) [also known asthe flexural modulus) which indicates stiffness of a material, and thesecond moment of area (or area moment of inertia I) (in m⁴), having SIunits of Pa·m⁴ which also equals N·m². The area moment of inertia I maybe calculated from the values of the inner diameter (ID) and the outerdiameter (OD) by a person skilled in the art using the formula[I=π/64(OD⁴−ID⁴)]. In one particular example discussed herein, theflexural rigidity value is calculated to be 0.0023 N·m² for the flexibleintermediate region 100 b comprising LDPE and 0.00086N·m² for the rigidproximal region 100 c comprising HDPE. In some embodiments, the ID ofthe dilator 100 along the flexible intermediate region 100 b and therigid distal end 100 a (not including the taper), ranges from betweenabout 0.056″ to about 0.06″. In some such embodiments, the OD of thedilator 100 along the flexible intermediate region 100 b and the rigiddistal end 100 a (not including the taper), ranges from between about0.109″ to about 0.113″. In some embodiments, the flexible intermediateregion 100 b comprising LDPE, has a rigidity that ranges from betweenabout 0.00030 N·m² to about 0.0014 N·m², and the rigid distal end region100 a comprising HDPE has a rigidity that ranges from between about0.0015 N·m² to about 0.0046 N·m².

In one particular example, the dilator 100 is usable with a steerablesheath 300 that is an 8.5 French unidirectional steerable sheath, asshown in FIG. 2A, that has a deflectable region or articulating portion200 b that is operable to deflect with a curve S having an angle ofabout 180 degrees and with a radius of curvature of about 8.5 mm. Thesteerable sheath 300 has a length equal to about 45 cm. In oneparticular example, the steerable sheath 300 may be a SUREFLEX™Steerable Sheath sold by Baylis Medical Company Inc., as shown in FIG.4. The steerable sheath 300 comprises a metal wire braid comprising aHigh Tensile 304v Stainless Steel 0.002″×0.006″ with a polymer jacketdisposed thereon, and an inner PTFE liner. The polymer jacket comprisessections of PEBAX and Nylon with varying durometers (D) and lengths. Thedeflectable portion of the steerable sheath 300 is indicated byreference number 200 b.

In one such embodiment, a steerable sheath assembly is described withthe dilator 100 being inserted within the steerable sheath 300. In aparticular example of this, the steerable sheath 300 is actuated toreach an angle of about 90 degrees. In one such example, the actualobserved deflection of the steerable sheath 300 is equal to about 80degrees. Thus, the steerable sheath 300 is able to reach about 88.8% ofits intended curvature. As such the dilator 100 allows the steerablesheath 300 to substantially reach its intended curvature. Conversely,unlike the embodiments of the present invention, when a rigid HDPEdilator with similar dimensions is used (i.e. a dilator with similar IDand OD that comprises entirely of HDPE) the steerable sheath 300 is onlyable to reach a 45 degree curvature which is about half of the intendedcurvature.

In an additional example, the steerable sheath 300 is actuated to reacha deflection angle of about 180 degrees, however, an actual deflectionequal to about 140 degrees is observed. Thus, the steerable sheath 300is able to reach 77.8% of its intended curvature. Contrary to this, whenthe steerable sheath 300 is used with a rigid HDPE dilator, thesteerable sheath 300 is only able to reach a 90 degree curvature.

In still an additional example, the steerable sheath 300 is actuated toreach a deflection angle of about 250 degrees with the actual observeddeflection being equal to about 180 degrees. Thus, the steerable sheathis able to reach about 72% of its intended curvature. On the other hand,when the steerable sheath 300 is used with a rigid HDPE dilator, thesteerable sheath 300 is only able to reach a curvature of about 110degrees.

As such, in the examples outlined above, the flexible intermediateregion 100 b of dilator 100, in accordance with an embodiment of thepresent invention, substantially does not inhibit the range of motion ofthe steerable sheath 300, allowing the steerable sheath 300 to reach itsintended shape or curvature in order to access a desired tissue sitewithin a region of tissue within a patient's body. Thus, in someembodiments the dilator 100 allows the steerable sheath to reach acurvature that is equal to at least about 70% of its intended curvature.In other embodiments the dilator 100 allows the steerable sheath toreach a curvature that is equal to greater than about 50% of theintended curvature.

In one particular embodiment, the dilator 100 is usable with anancillary device such that it allows the ancillary device to maintain orreach its intended shape or curvature in order to access a desiredtissue site within a region of tissue within a patient's body. Thedilator 100 may be of the type described herein above, that comprises arigid distal end region 100 a and a flexible intermediate region 100 bterminating at the distal end region 100 a, with the rigid distal endregion 100 a having a rigidity greater than the flexible intermediateregion 100 b to enable the dilator 100 to advance through tissue. Thedilator 100 is configured for use in conjunction with the ancillarydevice such that during use, the flexible intermediate region 100 bcorresponds to a region of the ancillary device that is functional forimparting or providing a curvature. In one particular example, thedilator 100 is advanced over or through the ancillary device such thatsuch that during use the flexible intermediate region 100 b of thedilator 100 does not affect the region of the ancillary device that isfunctional for imparting a curvature, allowing the ancillary device tosubstantially maintain or reach its intended position or shape in orderto position the dilator rigid distal end region 100 a at a desiredlocation within the region of tissue.

In one such example, the ancillary device comprises a steerable devicesuch as a sheath, catheter or guide-wire that is steerable, where theancillary device is functional for imparting a curvature by actuation ofthe ancillary device. When in use in conjunction with the dilator 100,the flexible intermediate region 100 b of the dilator does not inhibitor prevent the ancillary device from reaching its intended curvatureupon actuation to position the dilator distal end region 100 a at adesired location.

Alternatively in some embodiments, the ancillary device comprises afixed curve device such as a fixed curve sheath that has a preformedcurve Similar to embodiments discussed previously herein, the fixedcurve sheath is usable with the dilator 100 and during use the flexibleintermediate region 100 b of the dilator 100 does not affect thepreformed curvature of the sheath, thus allowing the sheath to positionthe rigid distal end 100 a of the dilator 100 at the desired locationwithin the region of tissue. Furthermore, the use of the dilator 100, inaccordance with an embodiment of the present invention, may prevent theneed for over curving the sheath in anticipation of a substantialdecrease in curvature of the sheath once the dilator 100 there-through.

In one such example, a fixed curve sheath is described with the dilator100 being inserted therein. The fixed curve sheath has a pre-formedcurve with an angle of about 40 degrees. Once the dilator 100 ispositioned through the fixed curve sheath, the curvature of the sheathis observed to be about 32 degrees. Thus, the fixed curve sheath is ableto maintain its curvature at about 80% of the intended curvature. Assuch the dilator 100 allows the fixed curve sheath to substantiallymaintain its intended curvature. Contrary to this, if a rigid HDPEdilator is utilized, unlike embodiments of the present invention (asdescribed previously herein above), the curvature of the fixed curvesheath is reduced to about 22.5 degrees.

Similarly in another example, a fixed curve sheath is described that hasa pre-formed curvature with an angle of about 135 degrees. Once adilator 100, is inserted through the sheath in accordance with anembodiment of the present invention, the observed angle of curvature ofthe fixed curve sheath, is equal to about 112 degrees. Thus, the fixedcurve sheath 300 is able to maintain a curvature that is equal to about77.8% of its intended curvature. Contrary to this, if a rigid HDPEdilator is utilized, unlike embodiments of the present invention, thecurvature of the fixed curve sheath is reduced to about 78 degrees.Thus, in some such embodiments, the fixed curve sheath is able tomaintain an angle of curvature that is greater than about 60% of itsintended curvature. In other embodiments, the fixed curve sheath is ableto maintain an angle of curvature that is equal to at least about 75% ofits intended curvature.

As outlined above, in some embodiments described herein above, thedilator 100 comprises varying regions of flexibility (i.e. rigid andflexible regions) to define a hybrid medical device. Since the dilator100 comprises a fairly constant OD and ID and thus fairly constant wallthickness along its length, the behavior of the various regions, interms of rigidity, is governed by the stiffness of the materials used.For example, the higher the stiffness of a material, the greater therigidity, and the lower the stiffness of the material the lower therigidity. Alternatively, in other embodiments, a single material may beused to form the dilator where the varying regions of flexibility areprovided by varying the wall thickness along the respective regions. Forexample, an HDPE dilator may be provided with a relatively thin wallthickness along the flexible intermediate region and a relativelythicker wall thickness along the distal end region, in order to providea dilator with the functionality described previously hereinabove.

Puncture Devices

In accordance with further embodiments of the present invention, asdescribed hereinabove, FIGS. 5A-5F illustrate embodiments of a medicaldevice operable to be guided to a tissue site to puncture tissue and tofunction as a rail for installing devices thereupon. Such embodimentsprovide efficiencies to medical procedures in which they are utilized asthey perform multiple functions and thereby reduce the amount of deviceexchanges that need to be performed. The “hybrid” medical devicesdescribed herein further facilitate the access and puncture of a tissuesite upon insertion at a particular access site on a patient's body, asdescribed hereinabove.

With reference to FIG. 5A, an embodiment of a medical device, referredto herein as multi-function guidewire 200, is shown. Multi-functionguidewire 200 includes an elongate member which comprises a proximalsection 206 which is typically curved, a rail section 204, and a distalsection 202 which is also typically curved. Multi-function guidewire 200is sufficiently flexible to enable access to heart tissue, such as aseptum, from, for example, an inferior approach or a superior approach.Thus, multi-function guidewire 200 allows access to a particular tissuesite from one of several vascular access sites. While certain aspectsand features of the multi-function guidewire 200 will be presentlydescribed with reference to one specific application, namely creating apuncture in a heart septum, it will be understood by those of skill inthe art that the medical device described herein is usable in variousapplications and its utility is not limited to this particularprocedure.

An active tip 208 (shown in detail in FIG. 5E) at the distal end of thedistal section 202 is operable to deliver energy for puncturing tissuesuch as a heart septum to create a puncture site through which distalsection 202 and the distal part of rail section 204 can be advanced, forexample to enter the left atrium. Once advanced through the puncturesite, distal section 202 is biased to form a coil for anchoringmulti-function guidewire 200 beyond the puncture site. Typically, whendistal section 202 is advanced out of a dilator and beyond the septum tocurl up into a coil in the left atrium, the distal end of the railsection will have been advanced into the left atrium i.e. in order forthe distal section to form a coil, rail section 204 is typicallyadvanced into the left atrium to define a rail thereto. In someembodiments, particularly for use in accessing the left atrium, thedistal section 202 is sized such that when it forms a coil in the leftatrium, the coil will not be accidentally advanced into openingsadjacent the left atrium, such as a left pulmonary vein or a mitralvalve. Once the guidewire is anchored, rail section 204 functions as asubstantially stiff rail for supporting the installation of one or moretubular members thereupon and for advancing devices into the heart. Intypical embodiments, rail section 204 includes a metal wire 212 (FIG.5B) which is fabricated of spring tempered steel. In some embodiments,for example when accessing the heart from a superior approach, the railis sufficiently flexible to bend about 180° and yet maintains sufficientrigidity to function as a rail for advancing devices thereover.Additionally, the flexibility of rail section 204 enables it to bemaneuvered (for example, by a steerable sheath) to access a tissue site.Thus, as described with respect to dilator 100 above, a medical devicesuch as multi-function guidewire 200 can be understood to be a “hybrid”device, having sufficient flexibility to be positioned at a tissue sitefrom a particular access site, while being sufficiently rigid tofunction as a rail for installation of other devices thereupon.

In some embodiments of the multi-function guidewire 200, rail section204 has a length of about 700 mm to about 1750 mm to enable access tothe tissue site. In some embodiments, the rail section has a length ofbetween about 1200 and 1300 mm, more particularly about 1240 mm.Typically, as shown in FIG. 5B, the rail section has a constant diameterin maximum rail portion 234 and tapers distally in tapered rail portion236. In some examples, the rail section (including metal wire 12 andinsulation 214, described further hereinbelow) has an outer diameter ofabout 0.86 mm (0.034 inches) at its proximal end (i.e. at maximum railportion 234) and about 0.71 mm at its distal end (i.e. at the distal endof tapered rail portion 236). In some such embodiments, the diameter ofthe guidewire elongate member is constant throughout maximum railportion 234. In some embodiments, the upper limit for the outer diameterof the proximal end of the rail section (including metal wire 12 andinsulation 214) is about 1.1 mm and the lower limit of the outerdiameter of the distal end of rail section 204 (distal end of taperedrail portion 236) is about 0.6 mm. In some alternative embodiments, theouter diameter tapers in maximum rail portion 234.

The proximal section 206 is biased to a coiled configuration forimproved handing of the medical device, for example to avoid interferingwith users of the device such as doctors, nurses and other medicalpersonnel. In some embodiments, the proximal section is biased to assumea spiral-shaped coil, while in other embodiments; it is biased to assumea constant diameter coil (i.e. the diameter across the entire coil issubstantially constant). In some embodiments, proximal section 206 has alength of about 150 to about 600 mm. In one specific example, proximalsection has a length of about 500 mm.

For ease of illustration of the primary sections of multi-functionguidewire 200, these sections are shown in FIG. 5B, as follows: thelower part of the figure shows the wire 212 of guidewire 200 in atypical configuration in use, with both distal section 202 and proximalsection 206 adopting a coil shape, while the upper portion of the figureshows the wire 212 in a straight configuration. The divisions betweenthe different sections of multi-function guide-wire 200 are shown byconstruction lines between the top and bottom drawings, with theexception of the two end parts, proximal section straight portion 215and distal section straight portion 216.

Referring to the straight configuration wire shown in the upper part ofFIG. 5B, proximal section 206 includes proximal section straight portion215 and proximal section curved portion 232. Typically, wire 212 has aconstant diameter in proximal section 206. Transition portion 222 islocated between proximal section 206 and rail section 204. The diameterof wire 212 increases distally through transition portion 222. Referringto the coiled configuration of wire 212, shown in the lower part of FIG.5B, proximal section straight portion 215 is shown at the bottom of thecoil formed by proximal section 206. The proximal end of straightportion 215 includes an exposed portion 212 a of electrically conductivewire 212.

Rail section 204 includes maximum (or ‘constant-diameter’) rail portion234 and tapered rail portion 236. Typically, maximum rail portion 234has a constant diameter along its length which generally corresponds tothe largest diameter of the wire. In some embodiments, the diameter ofwire 212 tapers distally through tapered rail portion 236.

Distal section 202 is distal of rail section 204 and includes distalsection curved portion 226 and distal section straight portion 216.Distal section straight portion 216 is shown, in the lower portion ofFIG. 5B, inside of the coil formed by distal section 202.

Typically, wire 212 is comprised of spring tempered stainless steel.

In some embodiments, wire 212 of the rail section has an outer diameterof about 0.64 mm (more specifically, 0.6 mm) at maximum rail portion 234and at a proximal end of the tapered rail portion 236 (i.e. the diameteris constant in maximum rail portion 234); and an outer diameter of about0.5 mm at a distal end of tapered rail portion 236 of the rail section204. More broadly, embodiments of the wire 212 of the rail section havean outer diameter ranging from about 0.89 mm and to about 0.36 mm, orabout 0.9 mm to about 0.3 mm, with the diameter of wire 212 typicallybeing constant in maximum rail portion 234. In alternative embodiments,the outer diameter tapers in maximum rail portion 234.

In some embodiments, the proximal end of rail section 204 (i.e. theproximal end of maximum rail portion 234) of wire 212 has a stiffness of2119 N/m or less. In some embodiments, the distal end of tapered railportion 236 has a stiffness of 118 N/m or more. Typically, the stiffnessis constant throughout the length of maximum rail 234, but it maydecrease distally in alternative embodiments. In one example, theproximal end of rail section 204 (the proximal end of maximum railportion 234) has a stiffness of about 550+/−5 N/m, more specifically 552N/m, and the distal end of tapered rail 236 has a stiffness of about200+/−5 N/m, more specifically 204 N/m, to enable the rail section to bebendable by at least 180 degrees and to function as a rail forsupporting installation of one or more tubular members thereupon. Inanother embodiment, the rail section has a stiffness of between about100 N/m to about 600 N/m. It should be noted that the stiffness valuesnoted herein are derived using a 3-point bend test over a 50 mm span, aswould be understood to those of skill in the art.

For ease of understanding, a table of correspondence is included forconverting certain of the stiffness measurements included herein tonormalized flexural rigidity:

Stiffness in three point bending over Wire diameter (mm) span of 50 mm(N/m) Flexural rigidity (N * m{circumflex over ( )}2) 0.635 552 1.4E−30.5 204 5.3E−4 0.89 2119 5.5E−3 0.43 118 3.1E−4 0.157 2.1 5.4E−6 0.1270.88 2.0E−6

The diameter of wire 212 (and thereby multi-function guide-wire 200)decreases distally along distal section curved portion 226 of the distalsection, and alternately decreases and increases distally in distalsection straight portion 216 (explained below, with reference to FIG.5F).

In typical embodiments, a layer of electrical insulation 214 (FIG. 5D)covers electrically conductive wire 212, with the exception of activetip 208 at the distal end of multi-function guide-wire 200 and anelectrically exposed portion 212 a at the proximal end of the guidewire,both of which remain electrically exposed. Exposed portion 212 a is partof proximal section straight portion 215 and is operable to beelectrically connected to an electrosurgical generator. Proximal sectionstraight portion 215 facilitates loading/installation of over-the-wiredevices (e.g. tubular members) onto the multi-function guidewire.

FIG. 5C is an exterior view of detail “A” of FIG. 5A showing distalsection 202. The distal section 202 includes a distal section straightportion 216 which is distal of a distal section curved portion 226.Distal section straight portion includes active tip 208. In someembodiments, a length of distal section 202 is about 30 mm to about150+/−10 mm. In some embodiments, a length of the distal section isabout 125 mm.

Distal section 202 is configured such that when it is advanced through apuncture site in tissue, such as cardiac structures, it assumes a coiledconfiguration whereby the active tip 208 is directed away from thetissue, and is positioned at a predetermined distanced from electricallyinsulated portions of distal section 202. Distal section straightportion 216 of distal section 202 advances forward along a substantiallystraight path (the “axis of advancement”) immediately after puncturingtissue and prevents the guidewire from immediately curling back onitself in order to potentially deliver energy a second time to thetissue site. When distal section straight portion 216 has beencompletely advanced out of a lumen (for example, the lumen of adilator), distal section curved portion 226 is configured such that,upon deployment of distal section 202 from a confined state (inside thelumen) along an axis of advancement, active tip 208 curves away from theaxis of advancement. For example, after puncturing a septum, theconfiguration of distal section 202 during and after deployment (FIG.5C) acts to prevent the electrode (active tip 208) from directlycontacting tissue on the left side of the heart, and from contacting thedistal section curved portion 226 of the guidewire. Positioning theactive tip 208 at a distance from distal section curved portion 226helps to ensure that the guidewire will not be damaged if energy isdelivered through active tip 208 once the coil configuration has beenachieved.

The configuration of a coiled distal section 202 is shown in FIGS. 5A,5C and 5D, which illustrate examples of an approximately 630° generallyspiral-shaped curve (also known as a double pigtail curve). Distalsection 202 (FIG. 5C) has an inner curve diameter d1 associated with aninner region of the 630° spiral-shaped curve and an outer curve diameterd2 associated with an outer region of the curve. Distal curves of somealternative embodiments range from about 270° to about 630°, with aspecific alternative embodiment having a 270° curve (a single pigtailcurve). Other alternative embodiments have curves of about 360° andabout 450°. Yet other alternative embodiments have distal section 202curves of less than 270°.

In some embodiments of the multi-function guidewire, inner curvediameter d1 is about 6 mm to about 30 mm, and in some embodiments isabout 10 mm. In some embodiments of the multi-function guidewire, outercurve diameter d2 is about 20 to about 40 mm, and in some specificembodiments is about 22 mm.

As previously mentioned and, distal section 202 is configured such thatactive tip 208 does not contact distal section curved portion 226. 31.FIG. 5C illustrates an example of a distal curved section in a coiledconfiguration in which active tip 208 is spaced a pre-determineddistance away from distal section curved portion 226. In the illustratedembodiment, active tip 208 is orthogonal (at a 90° angle) to the pointalong distal section curved portion 226 to which it is closest. In someembodiments, the distance of the active tip 208 from the insulatedportion of the distal section 202 to which it is orthogonal (i.e.closest to) ranges from about 0.8 mm to about 4 mm. In some embodiments,the pre-determined distance of the active tip from an insulated portionof the distal section which it is closest to, is about 2.8 mm.

The pre-determined distance of the active tip from the distal sectioncurved portion 226 of distal section 202 can also be measured relativeto the diameter of the active tip. Using this method of measurement, insome embodiments the pre-determined distance of the active tip from aninsulated portion of the distal section is equivalent to about 1 toabout 5 times a diameter of the active tip, and in a specific embodimentis equivalent to about 4.6 times a diameter of the active tip.

Distal section 202 is substantially atraumatic. It includes a roundedelectrode (active tip 208) for puncturing, not a sharp tip such as usedfor mechanical puncturing. Furthermore, distal section 202 issubstantially flexible (i.e. floppy) so as to avoid exertion oftraumatic forces on tissue (i.e. it acts as an atraumatic bumper) anddistal section 202 (with the exception of the rounded electrode) iscovered with a smooth layer insulation 214 (which may beanti-thrombogenic). In embodiments of the present invention, distalsection 202 does not contain any sharp edges or rough surfaces.

FIG. 5D is a cross section view of distal section 202 indicated bydetail “A” in FIG. 5A. Distal section 202 includes wire 212 withelectrical insulation 214 thereupon, marker 210, distal section straightportion 216, and active tip 208 at the furthermost distal tip of thewire. Marker 210 surrounds a distal segment of wire 212 and electricalinsulation 214 covers marker 210. Typically, active tip 208 is anelectrode operable to deliver electrical energy for puncturing tissue,and is radiopaque, whereby it also functions as a visibility markerunder medical imaging. In some embodiments, active tip 208 is formed bywelding together a radiopaque marker band with the distal end of wire212 to form a rounded electrode which is devoid of the layer ofelectrical insulation. Marker coil 210 may also be radiopaque and maycomprise a helical coil surrounding wire 212. Marker coil 210 helpsalign the active tip with target tissue (e.g. a fossa ovalis) duringtissue access and puncture procedures.

The outer layer of electrical insulation 214 covers wire 212 and marker210. In typical embodiments, electrical insulation layer 214 iscomprised of PTFE (Polytetrafluoroethylene) heat shrink. Whenmulti-function guidewire 200 is advanced through tissue, the friction ofthe tissue on insulation layer 214 creates a force that could possiblycause the insulation to slide proximally relative to wire 212, but asillustrated more clearly in FIG. 5F, electrical insulation layer 214extends distal of the helical coil 210, whereby the helical coil/markerhelps to secure the layer of electrical insulation to the multi-functionguidewire. Typically, marker coil 210 is welded, glued or otherwisesuitably coupled to wire 212. In some embodiments, the insulation layerhas a smooth outer surface to reduce the risk of thrombosis, and in someexamples is antithrombogenic.

The stiffness of distal section 202 enables it to provide anchorage toprevent multi-functional guidewire 200 from inadvertently slipping outto a position proximal of a puncture site. The stiffness of distalsection curved portion 226 decreases distally (i.e. it “tapers”). Insome embodiments of the multi-function guidewire, the proximal end ofdistal section curved portion 226 has a stiffness about 550+/−10 N/m orless, and the stiffness decreases distally, without abrupt changes, suchthat the distal end of distal section curved portion 226 has a stiffnessof about 1+/−0.5 N/m or greater, more specifically 0.88 N/m. In oneexample, a distal section curved portion 226 of the distal section has astiffness of about 200 N/m at its proximal end and a stiffness of about2.0 N/m, or more specifically 2.1 N/m, at its distal end.

In some embodiments, the stiffness of multi-function guidewire is mostlyprovided by wire 212, with electrical insulation 214 and marker 210providing negligible stiffness relative to the wire. As known to oneskilled in the art, the stiffness of multi-function guidewire 200 isrelated to (or a function of) the diameter of wire 212. In someembodiments of the multi-function guidewire 200, the wire 212 at theproximal end of the distal section curved portion 226 has an outerdiameter of about 0.64 mm or less. In some examples, the wire at thedistal end of distal section curved portion has an outer diameter ofabout 0.13 mm or more. In one example, the wire 212 of the distalsection curved portion tapers distally from a proximal end outerdiameter of about 0.5 mm to a distal end outer diameter of about 0.16mm.

In typical embodiments, the elasticity and stiffness of distal section202 make it possible for the multi-function guidewire to align with acurved lumen of a device, such as a dilator, containing themulti-function guidewire (i.e. to conform to a shape of a tubular memberwhile positioned within a lumen of the tubular member). Marker 210 aidsin positioning the distal end of the multi-function guidewire 200, inparticular, positioning active tip 208 before, during and afterpuncturing, and also in positioning devices that are advanced over theguidewire, such as pacemaker leads, thereby increasing the safety andefficacy of related medical procedures.

In some embodiments, marker/coil 210 is comprised of platinum andtungsten, and in one embodiment is comprised of platinum with about 8%tungsten. In most embodiments, the helical coil extends proximally fromthe active tip along a curve of about 180° to about 630°, and in oneexample along a curve of about 270°. Typically, the helical coil haslength of about 15 to about 100 mm, and in one example has length ofabout 30 mm.

In some embodiments, the outer diameter of multi-purpose guidewire 200(including wire 212, insulation layer 214 and coil 210, as applicable)at a proximal end of the distal section curved portion is about 0.86 mmor less, and a distal end of the distal section curved portion has anouter diameter which is about 0.59 mm or more. In one example, the outerdiameter of the proximal end of distal section curved portion is about0.72 mm and the outer diameter at the distal end of the distal sectioncurved portion is about 0.59 mm.

FIG. 5E illustrates an exterior view of distal section straight portion216. As shown in FIG. 5C, distal section straight portion 216 is distalof distal section curved portion 226. The distal section straightportion prevents distal section 202 from curving immediately uponexiting a lumen, for example, the lumen of a dilator. In someembodiments, distal section straight portion 216 has a larger diameterthan a distal end of the distal section curved portion 226. In mostembodiments, distal section straight portion has a length of about 3 toabout 10 mm, and in one example distal section straight portion has alength of about 6.5 mm.

FIG. 5F shows a cross-sectional view of distal section straight portion216 along the line A-A from FIG. 5E. FIG. 5F includes: distal sectionstraight portion 216, the distal end 228 of distal section curvedportion 226, wire 212, minimum diameter portion 230, constant diameterportion 224, and active tip 208.

Distal section straight portion 216 includes constant diameter portion224, which is a part of wire 212, and which typically has an outerdiameter ranging from about 0.13 mm to about 0.65 mm. In one particularexample, the diameter at the constant diameter portion 224 is about 0.25mm. The outer diameter of the constant diameter portion 224 is thelargest diameter of wire 212 within the distal section straight portion216. Wire 212 is has a larger diameter adjacent active tip 208 in orderto withstand the heat produced by active tip 208 without being damaged.

In some embodiments, the diameter of wire 212 at the minimum diameterportion 230 is the smallest diameter of wire 212 within distal sectionstraight portion 216, and is also the smallest diameter of wire 212 ofthe entire multi-function guidewire 200. The diameter of wire 212 atminimum diameter portion 230 typically ranges from about 0.13 mm toabout 0.64 mm, and in one example is about 0.16 mm, and is proximal ofthe constant diameter portion. The outer diameter of wire 212 increasesdistally from minimum diameter portion 230 to constant diameter portion224, i.e. wire 212 flares out distally (or has a reverse taper).

As previously described, active tip 208 is used for delivering energy,for example for puncturing tissue. In some embodiments, active tip 208is comprised of platinum and iridium, and in one embodiment is comprisedof platinum with 10% iridium. Typically, active tip is dome-shaped. Insome embodiments of the multi-function guidewire, the active tip 208 hasa diameter ranging from about 0.4 to about 0.7 mm, and in one examplehas a diameter of about 0.6 mm. Typically, active tip 208 has a lengthranging from about 0.75 mm to about 1.5 mm, and in one embodiment has alength of about 0.8 mm.

Referring back to FIG. 5B, proximal section 206 includes proximalsection curved portion 232 and proximal section straight portion 215,which includes exposed portion 212 a of wire 212.

While proximal section 206 is typically biased to a coiledconfiguration, it is also flexible which allows it to be uncoiled.Typically, wire 212 has a constant diameter throughout the proximalsection 206, with typical embodiments of the wire at proximal sectioncurved portion 232 having an outer diameter ranging from about 0.13 mmto about 0.64 mm, and in one example having an outer diameter of about0.38 mm. In some embodiments, the proximal section of theguidewire/elongate member (i.e. wire 212 as well as insulation layer214) has an outer diameter of about 0.60 mm.

In some embodiments, proximal section 206 is curved in the same plane asdistal section 202, i.e. the curves are coplanar. Having coplanarproximal and distal curves is advantageous in that, for example, whenthe distal section extends out of a dilator within the body, theorientation of the proximal curve outside of the patient's body can beused to ascertain the orientation of the distal curve, which itself maynot be directly visualized, in order to aid in positioning.

The configuration of proximal section straight portion 215 aids inloading over-the-wire devices onto the multi-function guidewire 200. Toassist in providing this functionality, the proximal section straightportion 215 is elongated and has a diameter less than or equal to therail section. In some embodiments, proximal section straight portion 215has a length of about 5 to about 50 mm, and in one embodiment, has alength of about 25 mm. To provide for greater user safety when loadingdevices onto the multi-function guidewire, proximal section straightportion 215 has a rounded tip.

An additional function of proximal section straight portion 215 isprovided by its relatively small diameter. Due to its size, proximalsection straight portion 215 is operable to puncture tissue mechanically(i.e. without the delivery of electrical energy). This allows a user theoption to potentially attempt both mechanical and electrical puncturesusing a single device. For example, a user may attempt mechanicalpuncture using the proximal end of the device and, if unsuccessful, theuser may withdraw the device and insert the distal end to attemptelectrical puncture. In some embodiments, the elongate member/guidewire200 at the proximal section, including wire 212 and insulation 214, hasan outer diameter of about 0.86 mm or less, with one embodiment havingan outer diameter of about 0.60 mm or less.

Multi-function guidewire 200 includes exposed portion 212 a of wire 212to allow for coupling to a source of electrical energy, for exampleusing a removable push-button connector placed over exposed portion 212a. In some embodiments, exposed portion 212 a has a length ranging fromabout 5 to about 15 mm, and in one example, has a length of about 10 mm.

Some embodiments of multi-function guidewire 200 include transitionalportion 222 between the proximal section 206 and rail section 204 toavoid having an abrupt change in diameter, for example to avoidstructural weaknesses. In some embodiments, the transitional portion 222defines a length ranging from about 15 mm to about 100 mm, with oneembodiment defining a length of about 25 mm. The proximal end oftransitional portion 222 has an outer diameter ranging from about 0.35mm to about 0.86 mm and the distal end has an outer diameter of about0.58 mm to about 1.12 mm. One particular embodiment has a minimum outerdiameter of about 0.60 mm and a maximum outer diameter of 0.86 mm.

In a specific embodiment of multi-functional guidewire 200, active tip208 is primarily comprised of platinum, with 10% iridium; marker 210 isa helical coil primarily comprised of platinum, with 8% tungsten; andeach of the proximal section 206, rail section 204, and distal section202 are comprised of a 304V stainless steel wire 212 (spring tempered)with PTFE heat shrink insulation (electrical insulation 214) thereupon.Stainless steel wire 212 has adequate stiffness to provide pushabilityto multi-functional guidewire 200 and is also an efficient electricalconductor.

In this specific embodiment, active tip 208 has a length of about 0.8 mmand a diameter of about 0.024 inches (˜0.61 mm); the wire 212 and activetip 208, combined, extend 2 mm beyond the distal end of marker 210; andmarker 210 has a length of about 3 cm. Furthermore, distal sectionstraight portion 216 has a length of about 6 to 10 mm and a diameter ofabout 0.018 to 0.0225 inches (0.45 to 0.57 mm)); distal section 202 hasan inner curve diameter d1 of about 1 to 3 cm and an outer curvediameter d2 of about 2 to 4 cm (FIG. 5C); the diameter of rail section204 adjacent the distal section 202 is 0.029 to 0.035 inches (0.74 to0.89 mm).

The specific embodiment further includes wire 212 of distal section 202having a length of 15 cm and tapering over the 15 cm segment of the wirefrom 0.025 inches (0.64 mm) to 0.006 inches (0.15 mm) at the tip of wire212. The tip of wire 212 has a length of 5.5 mm and a diameter of 0.010inches (0.25 mm) over the 5.5 mm length. The point along wire 212 thatis 15 cm from the distal tip of distal section 202 (i.e. the part ofdistal section 202 with the largest diameter of wire 212) has a proximalstiffness (force/displacement) of about 552 N/M. In this embodiment,active tip 208 is welded to wire 212. The distal tip of marker coil 210is 2 mm proximal from active tip 208 and has length of 30 mm. Electricalinsulation 214 is comprised of PTFE heat shrink and has a wall thicknessof 0.004 inches (0.10 mm).

Furthermore, in this specific embodiment, rail section 204 has a lengthof about 120 cm; and the wire 212 within the rail section has a diameterof about 0.635 mm±0.008 and stiffness of about 552 N/M. Proximal section206 has a length of about 525 mm±1.5, including a tapered section ofabout 2.5 cm (tapering down from the rail section), and the wire 212 ofproximal section 206 has a diameter of about 0.381 mm±0.008. The overalllength of wire 212 is 1800 mm±2.

Some alternative embodiments of multi-functional guidewire 200 comprisea straight proximal section 206 and/or a J-shaped distal section 202.

In alternative embodiments of the disclosed methods (described furtherhereinbelow), mechanical wires are used for puncturing. The mechanicalwires typically have a distal part/portion/section that is J-shaped toprevent accidental punctures and trauma by a sharp distal tip. Somealternative mechanical wire embodiments have a distal part that iscoiled, while others have a straight distal part.

Methods

A first broad aspect of a method of accessing a chamber of a patient'sheart using a superior access approach comprises the steps of: (a)advancing a steerable device through a patient's vasculature, from asuperior approach, into a heart of a patient, the steerable devicedefining a lumen and containing a dilator within the lumen; (b)articulating the steerable device to manipulate a distal portion of thedilator to position the dilator substantially adjacent a tissue; and (c)advancing the dilator through a puncture in the tissue. The procedure isperformed using forms of imaging known to those skilled in the art.

With reference now to FIG. 6A, in a particular embodiment, as describedherein, the steerable sheath 300 may be used to guide the dilator 100 toreach an area of the heart 400, in order for example to perform atransseptal puncture. In one such example, a guiding introducer orapparatus such as an introducer sheath may be advanced through thevasculature. A guide-wire may then be advanced through the introducersheath and advanced through the vasculature, for example the superiorvena cava 412, to be positioned within the right atrium 410. In someembodiments, the guide wire may be advanced without the use of anintroducer sheath. A dilator 100, in accordance with an embodiment ofthe present invention, may then be inserted through the steerable sheath300 forming a dilator and sheath assembly, or in other words a steerablesheath assembly 300 a.

Dilator 100 comprises a flexible intermediate region 100 b terminatingat a rigid distal end region 100 a. In the specific example shown, thedilator 100 additionally has a rigid proximal region 100 c, as describedpreviously, that helps minimize the risk of the dilator buckling as itis inserted into the steerable sheath 300. (Alternatively, a dilator 100may be provided with a softer proximal portion 100 c.) The dilator 100is usable with a steerable sheath 300, as described previously hereinabove. The steerable sheath 300 defines a lumen there-through forreceiving the dilator 100 and further comprises an articulating portionor deflectable region 200 b that terminates in a sheath distal end. Insome embodiments, the steerable sheath 300 and dilator 100 may beprovided as a steerable sheath kit.

Once the dilator 100 is inserted through the steerable sheath 300, thedilator 100 extends through the sheath lumen with the distal end region100 a of the dilator extending beyond the sheath distal end. Thus, insome embodiments, the dilator 100 is inserted through the steerablesheath 300 prior to the step of inserting the steerable sheath 300through the vasculature, and the steps of inserting and advancing thedilator 100 are performed substantially simultaneously with the steps ofinserting and advancing the steerable sheath 300. Once assembled, thedilator 100 and the steerable sheath 300 are configured to co-operatewith one another such that the flexible intermediate region 100 b of thedilator 100 corresponds to the articulating portion or deflectableregion 200 b of the steerable sheath 300 during use.

In alternative embodiments, the steps of inserting and advancing thesteerable sheath 300 may be performed prior to the steps of insertingand advancing the dilator 100. In a specific example, the steerablesheath 300 may initially be advanced into the right atrium 410, with acatheter or any other dilator inserted there-through, such as a seconddilator. The catheter or second dilator may then be swapped out with theflexible dilator 100. That is the catheter or second dilator may beremoved and the dilator 100 may be inserted through the sheath andadvanced into the right atrium. In still further alternativeembodiments, the steps of inserting and advancing said dilator 100 maybe performed prior to the steps of inserting and advancing saidsteerable sheath 300, which for example, may be advanced over thedilator 100.

After positioning the steerable sheath assembly 300 a within the rightatrium 410, the initial guide-wire is swapped out with an RF guide-wireor other energy delivery device (such as RF guidewire 200 visible inFIG. 6C). Referring now to FIG. 6B, the steerable sheath 300 is thenactuated to allow the steerable sheath 300 to achieve a desireddeflection angle to position the dilator distal end region 100 a at adesired location within a region of tissue, within a patient's body, forexample a desired location within the septum 422 of the heart 400 (insome examples, more specifically, at the fossa ovalis region of theseptum 422). The dilator 100 provides a flexible intermediate region 100b that does not hinder the ability of the steerable sheath 300 to curlor curve and as such allows the articulating portion or deflectableregion 200 b of the steerable sheath 300 to deflect upon actuation toposition the dilator 100 and the RF guide-wire as desired. As such, thesteerable sheath 300 is able to reach its intended curvature, as shownby path 300 b, upon actuation, to position the distal end region 100 aof the dilator 100 as well as a distal end of the RF guide-wire at theseptum 422. Using a dilator lacking such a flexible intermediate regionmay result in the steerable sheath not being able to achieve therequired or intended curvature, whereby the steerable sheath assemblymay be limited to the curvature shown in FIG. 6A.

Additionally, as outlined previously, the dilator 100 is essentially astraight dilator that is lacking a curve. As a result the dilator 100does not interfere with the curvature of the steerable sheath 300 byimparting a curvature to the steerable sheath 300. Thus, the lack ofcurvature in the dilator 100 in conjunction with the flexibleintermediate region 100 b, additionally aids in allowing the steerablesheath 300 to attain the required deflection angle or curvature toposition the dilator distal end region 100 a as well as the RFguide-wire at the septum 422.

With reference now to FIG. 6C, once the distal end region 100 a of thedilator 100 has been positioned at the septum 422, a transseptalpuncture may then be performed, for example by using a puncturing deviceas described hereinabove. In one embodiment, as shown, the puncturingdevice comprises the RF guidewire 200 (that was previously positionedwithin the steerable sheath assembly 300 a) which may then be activatedto deliver RF and be advanced across the septum 422 to create thepuncture. The guidewire 200 may then be advanced into the left atrium408 of the heart 400, as shown in FIG. 6C. The dilator 100 may then beadvanced over the guidewire 200 through the septum 422 in order todilate the transseptal puncture site, as shown in FIG. 6D, for examplein order to facilitate tracking of other devices through the puncturesite. The steerable sheath 300 and the dilator 100 may then be withdrawnand the other devices may be advanced over the guidewire 200, forexample, to perform a procedure within the heart.

FIGS. 7A to 7G illustrate the steps of an alternate embodiment of amethod for gaining access to the left side of a heart. Anatomicalfeatures illustrated in FIG. 7A include: heart 400, left ventricle 402,right ventricle 404, mitral valve 406, left atrium 408, right atrium410, superior vena cava 412, inferior vena cava 414, aorta 416, andbrachiocephalic veins 418.

FIG. 7B(i) shows access being gained through the left subclavian vein420, which is superior (i.e. above) to heart 400. In some alternativeembodiments a large diameter, short length introducer (not shown indrawings), known to those skilled in the art, is secured at the leftsubclavian access site to accommodate the steerable sheath. In theembodiment of FIG. 7B(i), steerable sheath 300 is advanced through leftsubclavian vein 420. Steerable sheath 300 is controlled using steerablesheath handle 302. Dilator 100, which includes dilator hub 102, isinserted into steerable sheath 300. Typically dilator 100 and steerablesheath 300 are locked together before being advanced through thevasculature to form a steerable sheath assembly. FIG. 7B(i) also showsthat a wire 200 is inserted into dilator 100.

As described above in the above embodiment of a method of the presentinvention, step (a) is for advancing a steerable device having a lumenand containing a dilator within the lumen, from a superior approach,into a heart of a patient. To arrive at the configuration of FIG. 7A, asteerable device, steerable sheath 300, is advanced through superiorvena cava 412 and right atrium 410, as indicated by sheath movementarrow 310, and temporally positioned in inferior vena cava 414. FIG. 7Aillustrates the position of apparatus upon a completion of step (a).From the position shown in FIG. 7A, steerable sheath 300 and dilator 100are slightly withdrawn to position the dilator's distal tip 106 in rightatrium 410. In alternative embodiments of the method, steerable sheath300 is not advanced into inferior vena cava 414, but instead,advancement is stopped when the distal tip of the steerable sheath isstill in right atrium 410. Steerable sheath 300 defines a lumen andcontains a dilator 100 within the lumen. Typically, the physicianselects the dilator and steerable sheath to match the outer diameter ofdilator 100 with the inner diameter of steerable sheath 300 (i.e. sothat the dilator fits snugly within the sheath or, put differently, thatthe dilator is cooperatively fitted to the sheath) so that the dilatormay provide support for the sheath to prevent the sheath from bucklingwhen making sharp turns, such as when, for example, steering the sheathtowards the atrial septum after the sheath is advanced through thesuperior vena cava. Furthermore, matching the outer diameter of dilator100 with the inner diameter of steerable sheath 300 facilitates smoothadvancement through the vasculature by avoiding and/or reducing scrapingof tissue.

Once the dilator's distal tip 106 is advanced into right atrium 410, thetip is positioned within the right atrium using the steerable sheath.The portion of the dilator shaft 104 of dilator 100 inside of rightatrium 410 (and within steerable sheath 300) is flexible enough to becooperatively steered by the sheath i.e. sheath 300 can manipulatedilator shaft 104 to the required angle to contact tissue without thedilator restricting the sheath's range of motion. Only the portion ofdilator shaft 104 within the part of steerable sheath 300 that is beingbent for the “U-turn” from the superior vena to contact the atrialseptum needs such a high degree of flexibility: the disclosed method canstill be performed even if other portions of dilator shaft 104 (notinside the right atrium) are relatively less flexible (i.e. more rigid)than the highly flexible portion.

Step (b) of the method is for the physician articulating the steerabledevice (steerable sheath 300), in the direction indicated by sheathmovement arrow 310, to cooperatively manipulate a distal portion of thedilator 100 and thereby position the dilator substantially adjacent atissue. The dilator is manipulated to arrive at the position shown inFIG. 7B. For the sake of simplicity, some embodiments of the method usea unidirectional sheath: the direction of deflection is known before theprocedure such that a bi-directional sheath is not required, although itmay be used as well.

FIG. 7B also shows dilator 100 slightly extended from steerable sheath300 and touching a tissue site (atrial septum 422). A flexible elongatepuncture member (medical device/guidewire 200) is located within thedilator's lumen when the physician adjusts steerable sheath 300 tocooperatively position dilator 100. Typically, the elongate puncturemember 200 is positioned to be close to, but not contacting, the fossaovalis of the atrial septum. The embodiment of guidewire 200 of FIG. 5Dhas radiopaque active tip 208 and radiopaque helical marker 210, whichwhen positioned towards the front of the dilator aid in positioningdilator 100 under imaging.

Typical embodiments of a method of the invention comprise the dilatorhaving a lumen (not shown in drawings) and containing an elongatepuncture member therein, and the method including between steps (b) and(c), advancing the elongate puncture member and puncturing the tissue.While the method is not limited to any particular type of tissue, in theillustrated embodiment the tissue is a septum of the heart and themethod comprises, between steps (b) and (c), advancing an elongatepuncture member (wire 200) and puncturing atrial septum 422, asillustrated in FIGS. 7C(i) to 7C(iii). In FIG. 7C(i), the distal tip ofdilator 100 is tenting the atrial septum 422 while the wire is advancedin the direction of wire movement arrow 220. The steerable device(steerable sheath 300) is used to position dilator 100 for tenting theseptum dilator under imaging. Tenting ensures the dilator is properlypositioned and in contact with the septum. FIG. 7C(iv) shows wire beingadvanced from the proximal end (the end toward the physician) andindicates diagrammatically the use of RF energy. FIG. 7C(ii) shows wire200 having just punctured atrial septum 422. The distal portion/part ofthe wire is comprised of a material with shape memory and it curves backas it is extended into left atrium 408. FIG. 7C(iii) shows the wirefurther extended and curving back approximately 270° into a “pig-tail”configuration (although, as described hereinabove, this coil maytypically traverse between 270° and 630°). FIG. 7C shows heart 400 withthe wire 200 that has punctured the septum and is in the position ofFIG. 7C(iii). As previously noted, curved distal part 202 acts toprevent the electrode (active tip 208) from directly contacting tissueon the left side of the heart.

In some embodiments of the method aspect of the present invention, theelongate puncture member is an energy delivery device, and puncturingtissue between steps (b) and (c) comprises delivering energy through theenergy delivery device (e.g. a distal end of the energy delivery device)to puncture the tissue. In some such embodiments, the energy deliverydevice is operable to deliver electrical energy, and in some specificembodiments, the electrical energy is in the RF range.

In some other embodiments, the elongate puncture member is a mechanicalwire with a sharp tip, and puncturing tissue between steps (b) and (c)comprises advancing the mechanical wire such that the sharp tip of themechanical wire punctures the tissue.

After wire 200 has punctured the septum, the physician proceeds to step(c) of the method. Step (c) is for advancing the dilator through apuncture in the tissue. The first broad aspect of the method includesthe use of a hybrid dilator having a flexible intermediate region 100 bthat can be bent from a superior approach to approach the septum, a bendof about 180° (i.e. a U-shaped turn), with the hybrid dilator alsohaving a distal tip that is sufficiently hard to provide for dilatingtissue without deformation of the taper. The use of the hybrid dilatormakes it unnecessary to use a soft dilator for steering and bending forthe U-shaped turn, and then changing to a stiffer dilator for crossingthe septum, whereby the hybrid dilator reduces the number of steps inthe procedure by eliminating the steps of withdrawing a soft dilator andadvancing a hard dilator.

FIG. 7D shows a positioning of the dilator after completion of step (c)of the method (advancing the dilator through a puncture in the tissue).Distal tip 106 of dilator 100 is comprised of hard (shape retaining)material that pushes aside tissue as dilator 100 is advanced. A portionof flexible intermediate region 100 b is shown extended from steerablesheath 300 inside of right atrium 410 in FIG. 7C. Typically, advancementof dilator 100 is stopped when maximum dilation is achieved; resultingin the dilator being positioned such that a distal portion of dilator'sdistal tip 106 is in left atrium 408 and a portion of distal tip is inright atrium 410. In alternative embodiments of the method, the dilatoris further advanced so that all of distal tip 106 is in the left atrium,such as, for example if the physician wants to ensure that maximumdilation has been achieved.

Some embodiments of the method aspects of the present invention furthercomprise a step (d) of withdrawing the elongate puncture member (andadvancing an anchor wire until the anchor wire bridges (crosses) theseptum and a right atrium to thereby provide a bridge between thesuperior vena cava and the left atrium (put differently, the anchor wirebridges the septum between the right and left atria). After an anchorwire is advanced, some embodiments further comprise a step (e) ofwithdrawing the dilator and sheath. FIG. 7E illustrates an installedanchor wire (wire 200) with the dilator and sheath withdrawn. Aspreviously described, curved distal part 202 of wire 200 providesanchorage to prevent wire 200 from inadvertently slipping back into theright atrium. The anchor wire is sufficiently stiff that it may, byitself, provide a rail for advancing medical devices into the leftatrium. Such medical devices are selected at the discretion of thephysician and can include, at least, ablation catheters and pacing leads(e.g. for left ventricular endocardial pacing). As described hereinaboveas well as hereinbelow, in an exemplary embodiment of a method of thepresent invention, a single wire may be utilized for both the puncturingstep as well as for anchoring in the left atrium by using a hybridmedical device, such as multi-function guidewire 200, to puncture thetissue site and provide a rail (as well as an anchor) through thepuncture site.

Some embodiments of the method aspect further comprise a step (f) ofadvancing a lead delivery catheter 350 (and possibly a lead deliverydilator, if dilator 100 may not be used for the stated purpose),configured for delivering leads (such as pacemaker leads), into the leftatrium of the heart, as shown in FIG. 7F. As previously described, othermedical devices are advanced/implanted in some alternative embodiments.

Some embodiments further include a step (g) of withdrawing the wire 200(as well as any dilators, including a lead delivery dilator). Some suchembodiments further comprise a step (h) of advancing the lead deliverycatheter 350 as indicated by catheter movement arrow 360 (FIG. 7F), tothereby position the distal end of lead delivery catheter 350 in leftventricle 402, as shown in FIG. 7G.

For some embodiments of this method aspect, a stiff introductory wire(rather than a hybrid wire such as guidewire 200) is used. Suchembodiments comprise: prior to step (a), advancing the stiffintroductory wire into the right atrium; and step (a) includes advancingthe steerable sheath and the dilator over the stiff introductory wire;and between steps (b) and (c), the stiff introductory wire is withdrawnand the elongate puncture member is advanced to puncture the septum. Insome such embodiments, the stiff introductory wire is comprised ofstainless steel. Typically, an introductory wire has an atraumatic tipthat is generally J-shaped.

In some embodiments, as noted above, a stiff introductory wire is notutilized; rather, a hybrid wire such as described above may be utilized.Such embodiments comprise: prior to step (a), the wire/elongate puncturemember is advanced into the right atrium; and step (a) includesadvancing the steerable sheath and the dilator over the wire/elongatepuncture member.

A further broad aspect of the method of accessing a chamber of apatient's heart using a superior access approach is described below. Themethod comprises the steps of: (a) advancing a steerable device througha patient's vasculature, from a superior approach, into a heart of apatient, the steerable device defining a lumen and containing anelongate puncture member within the lumen; (b) articulating thesteerable device to manipulate a distal portion of the elongate puncturemember for positioning the puncture member substantially adjacent atissue; (c) creating a puncture in the tissue using the puncture member;and (d) advancing a dilator over the puncture member through thepuncture.

This broad aspect relates to the concept of reducing or minimizing thenumber of steps in a procedure by using multifunctional or hybriddevices. First, embodiments of the second broad aspect include theelongate puncture member having a rail section that is stiff enough toprovide rail for advancing devices, thereby eliminating (makingunnecessary) using an anchor wire and the steps of withdrawing thepuncture member and advancing the anchor wire. Second, the steerabledevice is advanced over the puncture member, thereby eliminating the useof a stiff introductory wire and the steps for exchanging theintroductory wire and puncture member. Also, embodiments of the secondbroad aspect include the elongate puncture member being flexible enoughto be cooperatively manipulated by the steerable device, steerablesheath 300.

Making reference to FIGS. 7A to 7D, in some embodiments of this broadaspect: step (a) includes advancing the steerable device (e.g. steerablesheath 300) into the right atrium 410 of a heart 400; step (b) includesarticulating the steerable device (steerable sheath 300) to manipulate adistal portion of the elongate puncture member (wire 200) forpositioning the puncture member; step (c) includes advancing thepuncture member (wire 200) to create a puncture in the tissue (atrialseptum 422); and step (d) includes advancing dilator 100 over thepuncture member (wire 200) through the puncture in the tissue (atrialseptum 422). In some embodiments, step (c) further comprises advancingthe elongate puncture member into the left atrium. In some embodimentsthe method further includes a step (e) of withdrawing the steerabledevice and dilator, whereby the elongate puncture provides a rail foradvancing medical devices into the left atrium.

In some embodiments of the second broad aspect, the elongate puncturemember is an energy delivery device (e.g. a wire operable to deliverelectricity) and puncturing tissue in step (c) comprises deliveringenergy through the distal end of the energy delivery device to puncturethe tissue. In some other embodiments of the second broad aspect, theelongate puncture member is a mechanical wire with a sharp tip andpuncturing tissue in step (c) comprises advancing the mechanical wiresuch that the sharp tip of the mechanical wire punctures the tissue.

A specific embodiment of this broad aspect comprises the steps of: (a)introducing a steerable sheath and a soft dilator into the right atrium;(b) positioning the steerable sheath and the soft dilator such as to beaimed towards the septum; (c) withdrawing the soft dilator and advancinga stiffer dilator; (d) adjusting the steerable sheath to position thestiffer dilator, and an energy delivery device inside the dilator'slumen, substantially adjacent the atrial septum; (e) delivering energythrough the distal end of the energy delivery device to puncture theseptum; (f) advancing the energy delivery device until a distal tip ofthe energy delivery device crosses the septum and enters the left atriumwherein the portion of the energy delivery device bridging the rightatrium and septum is stiff enough to provide a device-supporting rail tothe left atrium; and (g) advancing the stiffer dilator to dilate thepuncture.

Some embodiments of this broad aspect include using a soft and a harddilator, while some alternative embodiments include using a hybriddilator as described hereinabove.

Details regarding characteristics of the initial broad aspect of anembodiment of a method of the present invention, including (but notlimited to) the description of tenting, the use of electricity and thedilator supporting the steerable sheath, also apply to the second broadaspect.

A further broad aspect of the method of accessing a chamber of apatient's heart using a superior access approach is described below. Themethod comprises the steps of: (a) advancing a steerable device througha patient's vasculature, from a superior approach, into a heart of apatient, the steerable device defining a lumen and containing a dilatorwithin the lumen; (b) articulating the steerable device to manipulate adistal portion of the dilator for positioning the dilator substantiallyadjacent a tissue; (c) advancing an elongate puncture member, fromwithin a lumen of the dilator, to create a puncture in the tissue; and(d) advancing the dilator over the elongate puncture member through thepuncture.

This broad aspect, similar to the first broad aspect mentioned abovewith respect to a method of the resent invention, also uses a hybriddilator. The use of the hybrid dilator renders unnecessary the use of asoft dilator for steering and bending, and then changing to a stifferdilator for crossing tissue, whereby the hybrid dilator reduces thenumber of steps in the procedure by eliminating the steps of withdrawinga soft dilator and advancing a stiffer (hard) dilator. Also, this broadaspect, similar to the second mentioned above, includes the elongatepuncture member having a rail section that is stiff enough to providerail for advancing devices, thereby eliminating (making unnecessary) theuse of an anchor wire and the steps of exchanging the puncture memberand anchor wire. Thus, this broad aspect includes embodiments of bothhybrid devices described hereinabove.

Making reference again to FIGS. 7A-7D, some embodiments of the methodcomprises the steps of: (a) advancing a steerable sheath 300 containingdilator 100 within a lumen of steerable sheath 300, from a superiorapproach, into a heart 400 of a patient; (b) articulating the steerablesheath 300 to manipulate a distal portion of dilator 100 for positioningthe dilator substantially adjacent atrial septum 422; (c) advancing anelongate puncture member (wire 200), from a lumen of dilator 100, tocreate a puncture in atrial septum 422; and (d) advancing dilator 100over wire 200 and through the puncture.

Similar to the previous broad aspects, step (c) comprises advancing theelongate puncture member to enter into the left atrium. In someembodiments of the third broad aspect, the method further includes astep (e) of withdrawing the steerable device and dilator to therebyprovide a rail for advancing medical devices into the left atrium.

In some embodiments of the third broad aspect, the elongate puncturemember is an energy delivery device and puncturing the tissue in step(c) comprises delivering energy through a distal end of the energydelivery device to puncture the tissue. In some other embodiments of thethird broad aspect, the elongate puncture member is a mechanical wirewith a sharp tip and puncturing the tissue in step (c) comprisesadvancing the mechanical wire such that the sharp tip of the mechanicalwire punctures the tissue.

A specific embodiment of this third broad aspect comprises the steps of:(a) introducing a steerable sheath and a dilator into the right atrium;(b) positioning the steerable sheath and the dilator such as to be aimedtowards the septum wherein the portion of the dilator shaft within thesteerable sheath is flexible enough to be cooperatively steered by thesheath; (c) adjusting the steerable sheath to cooperatively position thedilator, and an energy delivery device inside the dilator's lumen,substantially adjacent the atrial septum; (d) delivering energy throughthe distal end of the energy delivery device to puncture the septum; (e)advancing the energy delivery device until a distal portion tip of theenergy delivery device bridges (crosses) the septum and enters the leftatrium wherein the distal portion of the energy delivery device bridgingthe right atrium and septum is stiff enough to provide adevice-supporting rail to the left atrium; and (f) advancing the dilatorwhereby a shape-retaining (i e hard) tip section of the dilator dilatesthe puncture.

Details regarding the earlier broad aspects, including (but not limitedto) the description of tenting, the use of electricity and the dilatorsupporting the steerable sheath, also apply to this third broad aspect.

A fourth broad aspect of the invention is described below. Makingreference to FIGS. 7A to 7B, it is a method of accessing a chamber of apatient's heart using a superior access approach. The method comprisesthe steps of: (a) advancing an energy delivery device from an accesssite superior to the heart, through a superior vena cava and into aright atrium; (b) adjusting/articulating/manipulating a steerable deviceto position the energy delivery device substantially adjacent a septumof the heart; (c) delivering energy through a distal end of the energydelivery device to puncture the septum; (d) advancing the energydelivery device into a left atrium; and (e) advancing a dilator over theenergy delivery device whereby the dilator dilates the puncture.

The fourth broad aspect also relates to the concept of reducing orminimizing the number of steps in a procedure by using hybrid devices.Embodiments of the fourth broad aspect include using an energy deliverydevice (wire 200) having a rail section that is stiff enough to providerail for advancing devices, thereby making unnecessary using an anchorwire and eliminating the steps of withdrawing the energy delivery deviceand advancing the anchor wire.

Some embodiments of this aspect further comprise a step (f) ofwithdrawing the steerable device (steerable sheath 300) and the dilator100, after which the portion of the energy delivery device bridging theright atrium and septum is stiff enough to provide a device-supportingrail to the left atrium for advancing medical devices into the leftatrium.

Some embodiments of the fourth broad aspect include using a soft and ahard dilator, while some alternative embodiments include using a hybriddilator.

In some embodiments of the fourth broad aspect, the access site is at aleft subclavian vein 420. In some other embodiments, the access site isat a right subclavian vein. In yet some further embodiments, the accesssite is at a jugular vein.

Details regarding the first broad aspect, including (but not limited to)the description of tenting, the use of electricity and the dilatorsupporting the steerable sheath, also apply to the fourth broad aspect.

Thus, as described above, disclosed herein are several embodiments of amethod of providing access for medical devices to a specified tissuesite, such as the left side of the heart from a particular access site,such as superior access site. The method comprises using one or morehybrid devices for performing multiple steps of a medical procedure tothereby reduce and/or minimize the number of device exchanges. Some ofthe methods include puncturing the left side of the heart using anenergy delivery device sufficiently flexible so as to be advanced from asuperior approach and using the energy delivery device as a rail foradvancing other instruments thereupon, thereby providing a means ofsupport for advancing instrumentation through to the left side of theheart.

Further Examples

Example 1. A multi-function guidewire for a accessing a heart includinga septum, the multi-function guidewire comprising: a rail sectionsufficiently stiff to act as rail and flexible enough to enable accessto a septum from any approach; a distal section which is generallycurved and distal of the rail section; and an active tip at a distal endof the distal section, the active tip operable to deliver energy forpuncturing the septum to define a puncture site; the distal sectionbeing configured to form a coil whereby it anchors the multi-functionguidewire beyond the puncture site when the distal section is advancedbeyond the septum.

2. The multi-function guidewire of example 1, wherein the rail issufficiently flexible to enable access to the septum from an inferiorapproach and/or a superior approach.

3. The multi-function guidewire of example 1, wherein the rail sectionhas a maximum outer diameter of about 1.1 mm and a minimum outerdiameter of about 0.58 mm, or more particularly, an outer diameter ofabout 0.86 mm at its proximal end and about 0.72 mm at its distal end.

4. The multi-function guidewire of example 1, further comprising a metalwire, wherein the metal wire of a proximal curved portion of theproximal section has an outer diameter of about 0.13 to about 0.64 mmor, more specifically, an outer diameter of about 0.38 mm.

5. The multi-function guidewire of example 1, wherein the distal sectionis sized and configured to anchor a distal end of the multi-functionguidewire in an atrium without accidentally being advanced into openingsadjacent the left atrium such as a left pulmonary vein or a mitralvalve.

6. The multi-function guidewire of example 1, wherein the rail sectionhas a maximum elasticity of about 2100 N/m and a minimum elasticity ofabout 100 N/m.

7. The multi-function guidewire of example 1, wherein a distal curvedportion of the distal section has a maximum elasticity of about 550 N/mand a minimum elasticity of about 1 N/m.

8. The multi-function guidewire of example 1, wherein the distal sectioncomprises a spiral-shaped coil traversing a curve of about 630°.

9. The multi-function guidewire of example 8, wherein a diameter of aninner curve of the coil is between about 6 mm to about 30 mm or, morespecifically, about 10 mm.

10. The multi-function guidewire of example 8, wherein a diameter of anouter curve of the coil is between about 20 mm to about 40 mm or, morespecifically, about 22 mm.

11. The multi-function guidewire of example 1, wherein a diameter of theguidewire decreases distally along a distal curved portion of the distalsection.

12. The multi-function guidewire of example 11, wherein an outerdiameter of the guidewire at a proximal end of the distal curved portionis between about 0.72 mm to about 0.86 mm, and an outer diameter at adistal end of the distal curved portion is between about 0.59 mm toabout 0.72 mm.

13. The multi-function guidewire of example 1, wherein the distalsection further comprises a helical coil, the helical coil having alength of between about 15 mm to about 100 mm or, more particularly,about 30 mm.

14. The multi-function guidewire of example 13, wherein the helical coilis comprised of platinum and tungsten or, more particularly, wherein thehelical coil comprises about 8% tungsten.

15. The multi-function guidewire of example 1, wherein the active tip iscomprised of platinum and iridium or, more particularly, wherein theactive tip is comprised of platinum with 10% iridium.

16. The multi-function guidewire of example 1, wherein the proximalsection is biased to a curved configuration, the curved configurationbeing selected from the group consisting of a spiral-shaped coil and aconstant diameter coil.

17. The multi-function guidewire of example 1, wherein an outer diameterof the guidewire at the proximal section is between about 0.35 mm toabout 0.86 mm or, more particularly, about 0.6 mm.

Example 18. A dilator for use with a steerable sheath to access a regionof tissue within a patient's body, the steerable sheath defining a lumenthere-through for receiving the dilator and having a range of deflectionangles, the dilator comprising: a rigid distal end region; and aflexible intermediate region terminating at the distal end region; thedilator being configured for use in conjunction with the steerablesheath such that a location of the flexible intermediate regioncorresponds to a location of a region of the steerable sheath that isamenable to deflection; and the rigid distal end region having arigidity greater than the flexible intermediate region to enable thedilator to advance through tissue.

19. The dilator of example 18, wherein the dilator comprises asubstantially straight dilator.

20. The dilator of example 18, wherein the distal end region comprises arigid polymer and the intermediate region comprises a flexible polymer.

21. The dilator of example 20, wherein the rigid distal end region isformed from High Density Polyethylene and the flexible intermediateregion is formed from Low Density Polyethylene.

22. The dilator of example 18, wherein the flexible intermediate regionhas a length of between about 7 cm to about 17 cm or, more particularly,about 15 cm.

23. The dilator of example 18, wherein the rigid distal end region has alength of between about 0.4 cm to about 4.0 cm or, more particularly,between about 0.5 cm to about 1.0 cm or, even more particularly, betweenabout 0.6 cm to about 0.7 cm.

24. The dilator of example 18, wherein the dilator defines a taper.

25. The dilator of example 24, wherein the rigid distal end region formsa part of the taper.

26. The dilator of example 25, wherein the taper has a length of about 1cm.

27. The dilator of example 18, wherein the rigid distal end region has alength of between about 2.5% to about 60% of a length of said flexibleintermediate region.

28. The dilator of example 18, wherein the dilator further comprises aproximal region extending proximally from the flexible intermediateregion, the proximal region having a rigidity greater than the flexibleintermediate region.

29. The dilator of example 28, wherein the distal end region and theproximal region have a rigidity that is substantially equal.

30. The dilator of example 29, wherein the distal end region and theproximal region are formed from a rigid polymer and wherein theintermediate region is formed from a flexible polymer.

31. The dilator of example 30, wherein the distal end region and theproximal region are formed from High Density Polyethylene, and whereinthe flexible intermediate region is formed from Low DensityPolyethylene.

32. The dilator of example 29, wherein the rigidity of each of thedistal end region and the proximal region is equal to about 0.8 GPa andwherein the rigidity of the flexible intermediate region is equal toabout 0.3 Gpa.

33. The dilator of example 18, wherein the steerable sheath isactuatable to define a curve.

The embodiments of the invention described above are intended to beexemplary only. The scope of the invention is therefore intended to belimited solely by the scope of the appended claims.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the broad scope of theappended claims. All publications, patents and patent applicationsmentioned in this specification are herein incorporated in theirentirety by reference into the specification, to the same extent as ifeach individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

We claim:
 1. A medical device for puncturing tissue at a tissue site,the medical device comprising: an elongate member having a proximalsection, a distal section, and a rail section between the proximal anddistal sections; and, an active tip at a distal end of the distalsection, the active tip operable to deliver energy to create a puncturethrough the tissue; and, the rail section being configured to both actas a rail for supporting installation of one or more tubular membersthereupon, as well as to be maneuverable for enabling access to thetissue site.
 2. The medical device of claim 1, wherein the distalsection defines a distal section curved portion and a distal sectionstraight portion, the distal section straight portion being distal tothe distal section curved portion.
 3. The medical device of claim 2,wherein the elongate member comprises a reverse taper, wherein thereverse taper increases in outer diameter from the distal end of thedistal section curved portion to the distal section straight portion. 4.The medical device of claim 1, wherein the distal section defines adistal section curved portion configured to automatically form a distalcoil in a deployed state for anchoring the distal section upon thedistal section being advanced through the puncture.
 5. The medicaldevice of claim 4, wherein the coil is configured such that, upondeployment from a confined state, along an axis of advancement, theactive tip curves away from the axis of advancement.
 6. The medicaldevice of claim 4, wherein the distal section further comprises a distalsection straight portion distal to the distal section curved portion,the distal section straight portion including the active tip.
 7. Themedical device of claim 6, wherein the distal section straight portionhas a length of about 3 mm to 10 mm.
 8. The medical device of claim 4,wherein the distal coil is configured as a double pigtail curve.
 9. Themedical device of claim 1, wherein the elongate member comprises anelectrically conductive guidewire.
 10. The medical device of claim 9,wherein the electrically conductive guidewire is substantially coveredby a layer of electrical insulation with a distal tip of theelectrically conductive guidewire exposed.
 11. The medical device ofclaim 10, wherein the electrically conductive guidewire furthercomprises an exposed portion on the proximal section, wherein theexposed portion allows for coupling to a source of electrical energy.12. The medical device of claim 1, wherein the active tip issubstantially atraumatic.
 13. The medical device of claim 1, wherein themedical device further comprises a radiopaque marker positioned on thedistal section.
 14. The medical device of claim 13, wherein theradiopaque marker comprises a helical coil surrounding the elongatemember at the distal section.
 15. The medical device of claim 14,wherein the helical coil has a length of about 15 mm to about 100 mm.16. The medical device of claim 1, wherein the active tip comprises anelectrode.
 17. The medical device of claim 16, wherein the electrode isdome shaped.
 18. The medical device of claim 17, wherein the active tipfurther comprises a radiopaque marker band.
 19. The medical device ofclaim 1, wherein the active tip is configured to deliver radiofrequencyenergy.
 20. The medical device of claim 1, wherein the distal sectiondefines a J-shaped distal section.